1. Field of the Invention
The present invention relates to mobile devices. More particularly, the present invention relates to a mobile device comprising a disk storage system protected by a motion detector.
2. Description of the Prior Art
Integrating a disk storage system into a mobile device (e.g., a handheld computer such as a personal digital assistant (PDA), cellular phone, digital camera, tablet computer, etc.) provides a significant amount of non-volatile data storage for a relatively low cost. A disk storage system comprises a head flying just above the surface of a rotating disk. The head is attached to the distal end of an actuator arm which is rotated about a pivot by a voice coil motor in order to actuate the head over the disk. The disk comprises a magnetic coating which is magnetized by an inductive element in the head in order to write magnetic transitions onto the surface of the disk representing the recorded data. During a read operation, a read element in the head (e.g., inductive or magnetoresistive) detects the magnetic transitions to generate a read signal that is demodulated into an estimated data sequence representing the recorded digital data. Physical shocks can cause the head and actuator arm assembly to deviate off track and over-write data in adjacent tracks before the servo system detects the error. In addition, the head and the media can be damaged if the head xe2x80x9cslapsxe2x80x9d onto the surface of the disk. Physical shocks due to impacts with the ground or other hard objects (hereinafter foreign objects) are of particular concern for mobile devices due to their potentially abusive operating environment.
There is, therefore, a need for a mobile device capable of detecting an impending impact with a foreign object so that protective measures can be taken to prevent damage to the data, heads or media.
The present invention may be regarded as a mobile device comprising a disk storage system including a disk and a head actuated over the disk, wherein the disk comprises a data area. The mobile device further comprises a motion detector for detecting a relative velocity and distance of a foreign object with respect to the mobile device. When the motion detector detects an impending impact with the foreign object, retracting circuitry within the mobile device retracts the head away from the data area of the disk.
In one embodiment the motion detector comprises at least one transducer. In one embodiment the at least one transducer rotates to perform an omni-directional scan around the mobile device. In an alternative embodiment, the motion detector comprises a plurality of transducers. In one embodiment, the plurality of transducers are arranged to form a substantially concentric scan from a predetermine point on the mobile device. In yet another embodiment, each transducer is activated in a predetermined sequence to perform an omni-directional scan around the mobile device. In still another embodiment, the plurality of transducers are distributed at predetermined locations about the mobile device.
In one embodiment, the transducer comprises a sonar transducer. In one embodiment, the sonar transducer operates in an ultrasonic range. In an alternative embodiment, the transducer comprises a radar transducer, and in yet another embodiment the transducer comprises an optical transducer.
In one embodiment, the transducer comprises wireless communication circuitry for implementing a wireless communication function for the mobile device.
In one embodiment, the mobile device further comprises impact-detect circuitry for detecting an effect of the impact with the foreign object, wherein operation of the motion detector is adapted in response to detecting the effect of the impact with the foreign object.
The present invention may also be regarded as a mobile device comprising a disk storage system including a disk, a head actuated over the disk, and a preamp for applying a write current to the head during a write operation. The mobile device further comprises a motion detector for detecting a relative velocity and distance of a foreign object with respect to the mobile device. When the motion detector detects an impending impact with the foreign object, the write current is disabled.
The present invention may also be regarded as a method of operating a mobile device comprising a disk storage system including a disk and a head actuated over the disk, the disk comprising a data area. The method comprises the steps of detecting a relative velocity and distance of a foreign object with respect to the mobile device, and retracting the head away from the data area of the disk when an impending impact with the foreign object is detected.
The present invention may also be regarded as a method of operating a mobile device comprising a disk storage system including a disk and a head actuated over the disk, wherein a write current is applied to the head during a write operation. The method comprises the steps of detecting a relative velocity and distance of a foreign object with respect to the mobile device, and disabling the write current when an impending impact with the foreign object is detected.